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FreeBSD-SA-10:03.zfs                                        Security Advisory
                                                          The FreeBSD Project

Topic:          ZFS ZIL playback with insecure permissions

Category:       contrib
Module:         zfs
Announced:      2010-01-06
Credits:        Pawel Jakub Dawidek
Affects:        FreeBSD 7.0 and later.
Corrected:      2009-11-14 11:59:59 UTC (RELENG_8, 8.0-STABLE)
                2010-01-06 21:45:30 UTC (RELENG_8_0, 8.0-RELEASE-p2)
                2010-01-06 21:45:30 UTC (RELENG_7, 7.2-STABLE)
                2010-01-06 21:45:30 UTC (RELENG_7_2, 7.2-RELEASE-p6)
                2010-01-06 21:45:30 UTC (RELENG_7_1, 7.1-RELEASE-p10)

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

ZFS is a file-system originally developed by Sun Microsystems.

The ZFS Intent Log ("ZIL") is a mechanism that gathers together in memory
transactions of writes, and is flushed onto disk when synchronous
semantics is necessary.  In the event of crash or power failure, the
log is examined and the uncommitted transaction would be replayed to
maintain the synchronous semantics.

II.  Problem Description

When replaying setattr transaction, the replay code would set the
attributes with certain insecure defaults, when the logged
transaction did not touch these attributes.

III. Impact

A system crash or power fail would leave some file with mode set
to 07777.  This could leak sensitive information or cause privilege
escalation.

IV.  Workaround

No workaround is available, but systems not using ZFS are not
vulnerable.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 7-STABLE or 8-STABLE, or to the
RELENG_8_0, RELENG_7_2, or RELENG_7_1 security branch dated after the
correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 7.1, 7.2,
and 8.0 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 7.x]
# fetch http://security.FreeBSD.org/patches/SA-10:03/zfs712.patch
# fetch http://security.FreeBSD.org/patches/SA-10:03/zfs712.patch.asc

[FreeBSD 8.0]
# fetch http://security.FreeBSD.org/patches/SA-10:03/zfs.patch
# fetch http://security.FreeBSD.org/patches/SA-10:03/zfs.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

3) Examine the system and look for affected files.

These files can be identified with the following command:

# find / -perm -7777 -print0 | xargs -0 ls -ld

The system administrator will have to correct these problems if there
is any files with such permission modes.  For example:

# find / -perm -7777 -print0 | xargs -0 chmod u=rwx,go=

Will reset access mode bits to be readable, writable and executable
by the owner only.  The system administrator should determine the
appropriate mode bits wisely.

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

CVS:

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_7
  src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_replay.c 1.6.2.3
RELENG_7_2
  src/UPDATING                                             1.507.2.23.2.9
  src/sys/conf/newvers.sh                                  1.72.2.11.2.10
  src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_replay.c
                                                              1.6.2.1.4.1
RELENG_7_1
  src/UPDATING                                            1.507.2.13.2.13
  src/sys/conf/newvers.sh                                   1.72.2.9.2.14
  src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_replay.c
                                                              1.6.2.1.2.1
RELENG_8
  src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_replay.c 1.8.2.2
RELENG_8_0
  src/UPDATING                                              1.632.2.7.2.5
  src/sys/conf/newvers.sh                                    1.83.2.6.2.5
  src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_replay.c 1.8.4.1
- -------------------------------------------------------------------------

Subversion:

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/7/                                                         r201679
releng/7.2/                                                       r201679
releng/7.1/                                                       r201679
stable/8/                                                         r199266
releng/8.0/                                                       r201679
head/                                                             r199157
- -------------------------------------------------------------------------

VII. References

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-10:03.zfs.asc
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